Your CPU should be fine for a 1060, I believe they have a decent boost speed.....something like 4.2GHz.
Depending on where you live, but here (in New Zealand) the used prices of graphic cards has really dropped, and the 1060 6GB can be picked up for half the new price, but even if you did buy new, it's still worth it. The performance increase over an RX 460 will be huge.